Kenya police used teargas to disperse Raila Odinga's supporters who had gathered along Mombasa Road in the capital Nairobi to welcome him back to the country Friday.
The opposition National Super Alliance (Nasa) leaders had mobilised their followers to march to the Jomo Kenyatta International Airport to receive Mr Odinga who had been on a 10-day visit to the US.
As the plane carrying him touched down a few minutes after 11am, the police engaged his supporters, who wanted to force their way into the heavily guarded airport, in running battles.
About 200 supporters are reported to have beat the security cordon and entered the airport to receive him.
Mr Odinga is expected to address a rally at Uhuru Park in the capital's city centre.
Several vehicles were destroyed and a few motorists were injured during the chaos on Mombasa Road.
A police officer was injured during the fracas after he was hit by a stone hurled by a Nasa supporter.
Police had a rough time controlling traffic on one of the country's busiest and a key road that links the port of Mombasa to landlocked countries in East and Central Africa.